Ultraviolet radiation screening compounds

Abstract

Amongst the diversity of methods used by organisms to reduce damage caused by ultraviolet (UV) radiation, the synthesis of UV-screening compounds is almost ubiquitous. UV-screening compounds provide a passive method for the reduction of UV-induced damage and they are widely distributed across the microbial, plant and animal kingdoms. They share some common chemical features. It is likely that on early earth strong selection pressures existed for the evolution of UV-screening compounds. Many of these compounds probably had other physiological roles, later being selected for the efficacy of UV screening. The diversity in physiological functions is one of the complications in studying UV-screening compounds and determining the true ecological importance of their UV-screening role. As well as providing protection against ambient UV radiation, species with effective screening may also be at an advantage during natural ozone depletion events. In this review the characteristics of a wide diversity of UV-screening compounds are discussed and evolutionary questions are explored. As research into the range of UV-screening compounds represented in the biosphere continues, so it is likely that the properties of many more compounds will be elucidated. These compounds, as well as providing us with insights into natural responses to UV radiation, may also have implications for the development of artificial UV-screening methods to reduce human exposure to UV radiation.

Destruction of Raman biosignatures by ionising radiation and the implications for life detection on Mars

“…These include photosynthetic pigments such as chlorophyll and accessory pigments including phycocyanin [4,7], ultravioletscreening compounds such as scytonemin [8] and β-carotene [1,4] shown in Fig. 6, photoprotection and antioxidant molecules like carotenoids [1], and compounds involved in nutrient scavenging such as oxalate [4].…”

The effects of ultraviolet radiation on photosynthetic performance, growth and sunscreen compounds in aeroterrestrial biofilm algae isolated from building facades

“…Enhanced solar ultraviolet radiation (UVR) due to stratospheric ozone depletion is a major stress factor for many phototrophic organisms in aquatic and terrestrial ecosystems (Franklin and Forster 1997;Cockell and Knowland 1999;Day 2001). Ultraviolet-A (UVA, 315-400 nm) and ultraviolet-B (UVB, 280-315 nm; C.I.E.…”

“…Another protective strategy is the biosynthesis and accumulation of UV-absorbing sunscreens, such as flavonoids in higher plants (Day 2001), scytonemin in cyanobacteria (Garcia-Pichel and Castenholz 1991) or mycosporine-like amino acids (MAAs) in various cyanobacteria and marine organisms (Dunlap and Shick 1998). MAAs are water-soluble low-molecular-weight molecules with maximum absorption bands between 310 and 360 nm (Cockell and Knowland 1999). So far, about 20 different MAAs have been identified in mainly aquatic organisms from a wide taxonomic range (Cockell and Knowland 1999).…”

Phylogenetic analysis of genes involved in mycosporine-like amino acid biosynthesis in symbiotic dinoflagellates

“…They are found in many marine and freshwater organisms including cyanobacteria, fungi, macro-and micro-algae, as well as higher order animals such as cnidaria, fishes, arthropods, rotifers, mollusks, tunicates, and echinoderms (Sinha et al 2007). MAAs absorb light in the range of UV-A (315-400 nm) and UV-B (280-315 nm) with a maximum absorbance between 310 and 362 nm and molar absorptivity of ε028,100-50,000 M -1 cm -1 (Cockell and Knowland 1999;Dunlap and Shick 1998;Sinha et al 2007). MAAs and mycosporines were originally discovered in fungi and proposed to be involved in UV-induced sporulation (Trione et al 1966).…”

“…Scytonemin is a yellowbrown pigment only found in cyanobacteria absorbing radiation within the UV-A wavelength region, with an absorption maximum in vivo at 370 nm (Sinha and Häder 2008). It has been proposed that UV-absorbing compounds found in cyanobacteria, such as scytonemin and MAAs, played an important role in the protection from a high UV radiation in the past when Earth's atmosphere was devoid of oxygen (Cockell and Knowland 1999).…”